Yanmar 8LV main video
Yanmar's 8LV is a light-weight V8 producing 370-hp. Weighing in at only 992 lbs. (450 kg) the new 8LV is the lightest diesel engine in class, has the best power-to-weight ratio. It is even lighter than gas engines of similar horsepower. We think this relatively new Yanmar diesel opens up a lots of new, very interesting possibilities -- both in new boats and in re-power applications.

Yanmar 8LV Captain's Report

Yanmar has added a solid aluminum top cover. This will please every owner with a mechanic who lies across the top of the engine when servicing. All the components are within easy reach, and CAN-Bus technology includes an electronic CAN-bus control-head, versatile multi-function color display with NMEA2000 or J1939 gauge output, and an optional second station.

A Compact Package

Let's take a look at some of the features of this new engine. We discussed that it weighs in at 992 lbs. (450 kg), lighter than most of the big-block gas engines it can replace. The light weight and small dimensions of the 8LV will allow this engine to fit in a wide range of new boats and repower installations.

Comparison. A side-by-side comparison with one of Yanmar's popular 6-cylinder diesels demonstrates exactly how compact this package is. This 8LV is 8.5" (21.6 cm) wider, 1.75" (4.4 cm) higher, but 3.4" (8.6 cm) shorter than the popular Yanmar 315-hp 6LPA. In other words, this 8 cylinder engine can likely fit into any engine compartment that the 6 cylinder can, adding 55 hp and only 93 pounds of engine weight in the process.

Best Power-to-Weight Ratio in Class. The 8LV was designed for a specific task in mind and is not an "all-things-to-all-applications" engine. While some engines are designed for use in everything from trucks to backhoes to generators and therefore need a range power offerings that might span over 200 horsepower, the Yanmar 8LV models spans only 50 horsepower in its two basic configurations. That is far less than any of its competitors.

Much Less Weight. It is precisely because the Yanmar 8LV is so narrowly focused that its displacement can be less (4.47 L) compared to its competition (which are all well over 5 liters) and it can have a lower weight -- 400 to 500 pounds lighter. This is a huge difference that means that the 8LV can weigh from 40% to 50% less because they must be adaptable to more commercial applications.

Because it has a V-8 with cylinders at a 90-degree angle, the *LV is able to have a low profile.

Features

The 8LV has an rpm range from 550-3800 rpm. It is a four-stroke, 4.5 L engine with 8 cylinders arranged in a 90-degree V. The injection system is direct injection common rail.

180 AMPs.The electrical system is 12V and it packs a whopping 180 amp alternator, which means that a panel with lots of electronics can be powered without concern. The fresh water cooling is via an internal centrifugal fresh water pump, and a conventional rubber impeller on the seawater pump.

Max Efficiency Points. The factory tests show that the twin turbochargers cause the engine to reach maximum torque at just above 2000 rpm. A flat torque curve like this is very desirable for strong throttle response in the mid range. Fuel consumption charts show the best fuel economy is reached at about 3000 rpm, with plenty of power to spare if needed.

The new 8LV connects to either Yanmar’s sterndrive lower unit, a conventional marine gear, V-drive, or jet drive.

All Yanmar Components

One important aspect of this engine is that it's an all-Yanmar design, from the engine, to the drive, to the engine controls and displays. So what does this mean? For starters, when one company designs and builds every component, those components are all engineered to work perfectly together. And having one service contact for everything on a propulsion system is a very attractive feature. It means if something goes wrong, there is no finger-pointing among vendors. The buck stops with Yanmar.

Sterndrive Compatible

This engine is perfectly suited for Yanmar's newest and beefiest outdrive, the ZT370. One important feature to note about this particular outdrive is that it has hydraulic clutches like a marine gear. This means two things: first, there is no cone clutch, which has been used since the introduction of the sterndrive in the late '50s. Second, that annoying “clunk” that is heard when the drive is dropped into gear is eliminated, and the even more annoying “gear grinding” sound as the level is eased into gear is gone as well. When the Yanmar ZT370 is shifted into gear the drive engages in a whisper smooth fashion.

Digital Control

The 8LV is electronically controlled, so a digital control station makes operation easy and precise. The benefits of this type of control station are two-fold. First, there are no more push-pull mechanical cable runs from the control to the engine which can rust, jam or break (usually when docking). With Can-Bus technology it’s a simple wire run and the control station is plug-and-play.

Multiple Control Stations. This also means that adding components or even another control station, as in the case of a tuna tower or cockpit control station, is as simple as adding another wire run. Additionally, you now have a whole host of features in those controls at no extra cost, such as engine sync, neutral throttle control, single lever command, and individual drive trim controls. These were expensive options in the not so distant past.

Diagnostic Data. And since Yanmar has now refined how it talks to its engines, it is also easier for the engines to talk back to the operator with improved programmable displays. We can select from a series of displays to give us data on fuel consumption, MPG, temperatures, and pressure, among others. This data stream is compatible with large color displays showing such things as radar, depth, and even an engine room video.

With electronically controlled engines, it’s easy to decide what controls will be used, and where. In this instance, a sterndrive joystick is shown.

Digital controls provide the capability of synchronizing the engines with the touch of a button. Also single lever control, cruise mode, and individual trim adjustments are possible.

But What About Engine Longevity?

The question has been raised by the die-hard, old heavy diesel guys, “Can a light-weight diesel stand up?” That very question was posed to Yanmar and their response was, “We heard that concern 15 years ago with the introduction of the popular Yanmar 6LP. That engine has dominated the 300-hp class diesel range for over 10 years with a great track record for reliability and we even have customers with over 10,000 hours on that engine."

The Yanmar spokesman went on the say, “Yanmar has had one standard test protocol for marine engines over the past 25 years. Every new model must pass the rigorous testing before the name goes on it. We don’t test the newest light-weight engines any differently than we did the older heavier mechanical engines.”

The Back Cove 30 is powered by a single Yanmar 370-hp 8LV. It has a top speed of over 32 mph.

We Test the 8LV-370 Diesel

We tested the Back Cove 30 with a single 8LV-370. The Back Cove 30 is a popular Downeast style cruiser that has an LOA of 33'11'' (10.34 m), and a beam of 11'2" (3.4 m) and has a displacement of 12,000 lbs. (5,454 kg.). She utilized a standard inboard propulsion configuration. Her complete performance table can be seen below.

Best Cruise. As can be seen from the numbers above, she is holding plane at 2300 rpms and just 13.4 knots and from there to 3000 rpm she gets about the same fuel economy without a large "best cruise" spike. This is a good thing as it allows skippers to find the most comfortable speed for the conditions.

Twins. In twin-engine configurations the 8LV is appropriate in boats from 35' to 45' depending on their displacement and speed requirements. Her most efficient configuration is in all likelihood coupled to Yanmar ZT370 sterndrives.

The Wally/One yacht tender comes powered by twin Yanmar 8LV-370 engines as an option to the standard 315-hp Yanmar 6LPA engines. The builder says that with the twin 370s the boat can reach 47 knots.